1. Field of the Invention
The present invention relates to automatic range shifting in a manually shifted compound transmission having a lever-shifted main section connected in series with an auxiliary range section. In particular, the present invention relates to a range control for transmissions of the type described for automatically implementing driver-initiated range shifts which, under certain unusual operating conditions, will automatically implement range shifts not requested or initiated by the driver.
2. Description of the Prior Art
Controller-assisted, manually shifted transmission systems are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,582,558; 5,755,639; 5,766,111 and 5,791,189, the disclosures of which are incorporated herein by reference.
Compound transmissions having a range- and/or combined range-and-splitter-type auxiliary transmission section are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,754,665 and 5,390,561, the disclosures of which are incorporated herein by reference.
Compound transmissions having automatically implemented range shifting are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,911,787 and 5,974,906, the disclosures of which are incorporated herein by reference.
A semi-automated transmission having a hold mode wherein, under certain conditions, an automatic shift will occur while in the hold mode in the absence of a shift selection, may be seen by reference to U.S. Pat. No. 5,592,851, the disclosure of which is incorporated herein by reference.